People read for many different purposes, and they may read the same text very differently depending upon those purposes. Natural reading situations, as well as lab paradigms, vary in terms of their memory and their comprehension demands. Different cognitive operations may be required for immediate comprehension of meaning than for faithful preservation of lexical and structural information required for verbatim retention tasks. We will study the effects of task demands on the word-by-word reading times for text in which linguistic attributes are systematically varied. We will vary (a) the lexical, semantic and syntactic attributes of individual works, and (b) contextual factors that determine overall text difficulty, the amount of old vs. new information, and the interactions among words. We will measure reading times, subsequent comprehension and retention accuracy and subjective ratings of text: importance of individual words, their qualitative role in the sentence (key, support, relational), the locations of "natural divisions" and the number of ideas in text. We will use these data to test quantitative theories about the stages of cognitive and linguistic processing during perceptual coding of text. Our linear models account for reading time patterns characteristic of phrase structure coding exhibited when subjects read for faithful retention. We are developing models to account for the lexical-semantic patterns exhibited when Ss read for immediate comprehension. For a given body of text and a fixed performance task, individuals differ from one another in their patterns of word-by-word reading times, and presumably in their underlying reading strategy. We will examine individual RTs, and flexibility in reading stragegies (a) for fast vs. slow readers, (b) for good vs. poor readers (based on accuracy), (c) for variations in practice, (d) for two age groups (5th grade & college). The qualitative nature and the range of individual differences should have implications for reading instruction and remedial education.